The extradition hearing of former Mexico City Police Chief Arturo Durazo Moreno opened in federal court Wednesday with U.S. prosecutors charging that the once-powerful official used his position to amass "incredible wealth" during his six-year term.

Durazo, 68, whose palatial Mexico City home is now a federal "museum to corruption," is charged in his homeland with extorting payments from subordinates, failing to pay customs duty on his imported belongings and possessing illegal arms.

"We would like to submit this evidence of unexplained wealth," said Assistant U.S. Atty. J. Stephen Czuleger, signaling toward a table full of volumes of photographs, affidavits and other data. The evidence, most of which is contained in 12 heavy volumes, was wheeled into the courtroom in a shopping cart.

Among the documents are affidavits from policemen who said they were diverted from duty to build Durazo's Mexico City mansion with its race track, private disco and artificial lake; auxiliary chiefs who swore they had to pay Durazo percentages of their salaries to keep their jobs, and long lists of imported items that the Mexican government found in Durazo's homes and a warehouse.

"I would submit to you that the source of at least some of this illegal wealth is extortion," Czuleger said. He rested his case after submitting the documents into evidence.

Although no one outside his close circle of family and friends is believed to know the exact whereabouts of Durazo's fortune, his wealth has been estimated by U.S. sources at between $200 million and $300 million from business dealings, real estate, bribes, narcotics and peso trading in international markets.

The proceeding, which is being heard by U.S. Magistrate Volney V. Brown, is expected to take at least a week. The courtroom proceedings are expected to consist mostly of debates over technicalities of law.

The hearing is being held to determine if there is probable cause to extradite Durazo to stand trial in Mexico. The case is being heard here because Durazo established residency in Los Angeles when he left Mexico in early 1983, after his term in office expired.

The defense attorneys also hauled large numbers of documents into the courtroom on dollies and in cardboard boxes but did not reveal the contents of those documents Wednesday.

Instead, they challenged the validity of some of the prosecution's evidence, questioning paragraph by paragraph the admissibility of notarized documents, certain colorations of translation and whether potential witnesses against Durazo had personal knowledge of events they spoke of in their declarations.

Durazo is represented by at least seven attorneys: two prominent Mexico City criminal attorneys; San Francisco attorneys Bernard Zimmerman, James L. Warren and Jerrold Ladar, and Robert Talcott of Los Angeles. Talcott, a member of the Los Angeles Police Commission, said he is playing only a minor role in the defense.

Family in Court

The portly Durazo appeared relaxed as he listened to the proceedings amid heavy security and with the help of a translator. His wife, Silvia, and family and friends appeared in the courtroom but declined to speak with reporters.

Because Durazo is believed to harbor the secrets of some of Mexico's most powerful men, he is considered a possible target for assassination. He was arrested by the FBI in Puerto Rico last June on a sealed arrest warrant issued by Brown. He is being held without bail at an undisclosed federal institution.

Under the 1978 extradition treaty with Mexico, the U.S. attorney's office represents the Mexican government in its request to have Durazo returned. If Brown finds that there is probable cause for Durazo to stand trial in Mexico, the case will go to the State Department, which then will decide whether to extradite him.

Historically, the State Department has extradited those who have been ruled extraditable unless there are compelling diplomatic or political reasons for doing otherwise.